I could write programs in XML and write a machine to run them. <function name="main"><call function="print"><arg>Hello, World</arg></call></function> XML isn'

I could write programs in XML and write a machine to run them. <function name="main"><call function="print"><arg>Hello, World</arg></call></function> XML isn't a programming language in the same way ASCII isn't a programming language -- in the same way CSV isn't a programming language. Not because of turing completeness, but because they are a completely different thing.